PROJECT SUMMARY We advance innovative cardiorenal protective peptide therapeutics for heart failure (HF). Studies will investigate NPA7, a novel, multivalent and first-in-class peptide, engineered by the applicants to co-target two biological pathways. These two targets are the natriuretic peptide/particulate guanylyl cyclase-A receptor/cGMP and Angiotensin1-7/MasR/cAMP systems. We hypothesize that NPA7 mediates cardiorenal protective properties via these complementary pathways and has synergistic actions beyond pGC-A and MasR activation alone. Importantly, we also hypothesize that NPA7 is highly effective in a state of an overactive intrarenal renin-angiotensin-aldosterone system (RAAS) as NPA7 may suppress aldosterone production/release, antagonize AT1, suppress renin and inhibit angiotensinogen (AGT) in the kidney. Preliminary studies in experimental HF reveal that beyond sodium retention and congestion, there is activation of deleterious molecular pathways in the kidney for inflammation, apoptosis, and fibrosis, which may result in progressive worsening renal function and structure with poor outcomes. While multifactorial mechanisms may be involved in progressive renal structural and functional impairment in chronic HF, Angiotensin II (ANG II) is a fundamental mediator. Here NPA7, via pGC-A and MasR, may activate complementary RAAS inhibiting and antagonizing mechanisms with amplified cardiorenal protection. We also advance the concept that urinary AGT (uAGT), which drives the renal generation of ANG II, may serve as a novel pathophysiological biomarker for intrarenal RAAS activation, independent of circulating RAAS. Indeed, a major long-term goal is the development of uAGT as a novel urinary biomarker for intrarenal RAAS to aid in the identification of high-risk HF patients that may benefit from NPA7 therapy. Aim 1: Determine the cardiorenal protective properties of NPA7 in human renal tubular cells, cardiomyocytes and renal and myocardial fibroblasts in vitro. Aim 2: Determine cardiorenal protective and intrarenal RAAS suppressing properties of chronic NPA7 therapy in a large animal model of chronic HF that exhibits myocardial pump failure, reduced renal perfusion with congestion and markedly activated intrarenal RAAS compared to ACEi. Aim 3: Determine uAGT levels in high-risk chronic HF patients and its association with impaired renal function and its predictive power for future HF hospitalization and death.